How to send input to c++ through python

Question

I have used the following code to pass input to cpp program which reads input and prints it.

from subprocess import Popen, PIPE

p = Popen(['a.exe'], shell=True, stdout=PIPE, stdin=PIPE)
for ii in range(10):
    value = str(ii) + '\n'
    value = bytes(value, 'UTF-8')  # Needed in Python 3.
    p.stdin.write(value)
    #p.stdin.flush()
    result = p.stdout.readline().strip()
    print(result)

Following was the output of python

b''
b''
b''
b''
b''
b''
b''
b''
b''
b''

EDIT: Following is the code for cpp file

#include<iostream>
using namespace std;

int main()
{
    int a[10];
    for(int i=0;i<10;i++)
    {
        cin>>a[i];
        cout<<a[i];
        std::cout.flush();
    }
    return 0;
}

Answer 1

I tried code on Linux and I had two problems

• in Python I had to use full path to a.exe to run it

• in CPP I had to add << '\\n' because it sends text without \\n and p.stdout.readline() is waiting for \\n

Without full path I saw many b'' (and message "... not found" in first line)

Without << '\\n' script freezed because readline() was waiting for \\n

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EDIT: I forgot: I had to add p.stdin.flush() .

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EDIT: as @Sugar suggested in comment - use std::endl instead of "\\n"